Apparatus for growing thin films

ABSTRACT

The invention relates to an apparatus for growing thin films onto the surface of a substrate by exposing the substrate to alternately repeated surface reactions of vapor-phase reactants. The apparatus comprises at least one process chamber having a tightly sealable structure, at least one reaction chamber having a structure suitable for adapting into the interior of said process chamber and comprising a reaction space of which at least a portion is movable, infeed means connectable to said reaction space for feeding said reactants into said reaction space, and outfeed means connectable to said reaction space for discharging excess reactants and reaction gases from said reaction space, and at least one substrate adapted into said reaction space. At least one loading chamber is arranged to cooperate with said process chamber so as to permit said reaction space or a portion thereof to be moved into said process chamber and away from said process chamber and, further, the operating pressure of the loading chamber is arranged to be controllable independently from said pressure chamber.

PRIORITY INFORMATION

[0001] This application is a divisional of U.S. patent application Ser.No. 09/749,329, filed Dec. 27, 2000, which claims the priority benefitunder 35 U.S.C. §119 to Finnish Patent Application No. 19992798, filedDec. 28, 1999, the entire content of these applications are herebyexpressly incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an apparatus according forgrowing thin films on a surface of a substrate. More particularly, thepresent invention relates to an apparatus for producing thin films onthe surface of a substrate by subjecting the substrate to alternatelyrepeated surface reactions of vapor-phase reactants.

[0004] 2. Description of the Related Art and Summary of the Invention

[0005] Conventionally, thin-films are grown using vacuum evaporationdeposition, the Molecular Beam Epitaxy (MBE) and other similar vacuumdeposition methods, different variants of the Chemical Vapor Deposition(CVD) method (including low-pressure and organometallic CVD andplasma-enhanced CVD) or a deposition method of alternately repeatedsurface reactions called the Atomic Layer Epitaxy (ALE) method or AtomicLayer Deposition (ALD).

[0006] In MBE and CVD methods, the thin film growth rate is determinedby the concentrations of the provided starting material in addition toother process variable. To achieve a uniform thickness of the layersdeposited by these methods, the concentrations and reactivities ofstarting materials must be carefully kept constant on different surfaceareas of the substrate. If the different starting materials are allowedto mix with each other prior to reaching the substrate surface, as isthe case in the CVD method, for instance, a chance of their mutualreaction arises. Then, a risk of microparticle formation already withinthe infeed channels of the gaseous reactants is imminent. Suchmicroparticles generally have a deteriorating effect on the quality ofthe deposited thin film. Therefore, the possibility of prematurereactions in MBE and CVD reactors, for instance, is avoided by heatingthe starting materials not earlier than at the substrate surfaces. Inaddition to heating, the desired reaction can be initiated using, e.g.,a plasma discharge or other similar activating means.

[0007] In the MBE and CVD processes, the growth of thin films isprimarily adjusted by controlling the infeed rates of starting materialsimpinging on the substrate. In contrast, the growth rate in the ALEprocess is controlled by the substrate surface qualities, rather thanthe starting material concentrations or flow variables. The onlyprerequisite in the ALE process is that the starting material isavailable in sufficient concentration to saturate the surface of thesubstrate. The ALE method is described, e.g., in FI patent publications52,359 and 57,975 and in U.S. Pat. Nos. 4,058,430 and 4,389,973.Furthermore, equipment constructions suited to implement this method aredisclosed in patent publications U.S. Pat. No. 5,855,680 and FI 100,409.Apparatuses for growing thin films are also described in the followingpublications: Material Science Report 4(7) (1989), p. 261, andTyhjiötekniikka (Finnish publication for vacuum techniques), ISBN951-794-422-5, pp. 253-261. These references are incorporated herein byreference.

[0008] In the ALE growth method described in FI Pat. No. 57,975, thereactant atoms or molecules are arranged to sweep over the substrates,thus impinging on their surface until a fully saturated molecular layeris formed thereon. Next, the excess reactant and the gaseous reactionproducts are removed from the substrates with the help of inert gaspulses passed over the substrates or, alternatively, by pumping thereaction space to a vacuum before the next gaseous pulse of a differentreactant is admitted. The succession of the different gaseous reactantpulses and the diffusion barriers formed by the separating inert gaspulses or cycles of vacuum pumping result in a thin film growthcontrolled by the individual surface-chemical reactions of all thesecomponents. If necessary, the effect of the vacuum pumping cycle may beaugmented by the inert gas flow. For the function of the process, it istypically irrelevant whether the gaseous reactants or the substrates arekept in motion; it only matters to keep the different reactants of thesuccessive reactions separate from each other and to have them sweepsuccessively over the substrate.

[0009] Most vacuum evaporators operate on the so-called “single-shot”principle. In such an arrangement, a vaporized atom or molecule canimpinge on the substrate only once. If no reaction with the substratesurface occurs, the atom/molecule rebounds or is revaporized so as tohit the apparatus walls or the vacuum pump, undergoing condensationtherein. In hot-walled reactors, an atom or molecule that collides withthe process chamber wall or the substrate can undergo revaporizationand, hence, repeated impingements on the substrate. When applied to ALEprocess chambers, this “multi-shot” principle can offer a number ofbenefits including improved efficiency of material consumption.

[0010] ALE reactions operating on the “multi-shot” principle generallyare designed for the use of a cassette unit in which a plurality ofsubstrates can be taken simultaneously into the process chamber. In amodified arrangement, the substrates can be placed unmountedly into theprocess space formed by a pressure vessel, whereby the process spacealso serves as the reaction chamber wherein the vapor-phase reactantsare reacted with the substrate surface in order to grow thin filmstructures. If a cassette unit designed for holding several substratesis employed, the reaction chamber is formed in the interior of thecassette unit. Use of a cassette unit shortens the growth time persubstrate in respect to single-substrate cycling, whereby a higherproduction throughput is attained. Furthermore, a cassette unit arrangedto be movable into and out from the process chamber can be dismantledand cleaned without interrupting the production flow because onecassette unit can be used in the process chamber while another one isbeing cleaned.

[0011] Batch processing is preferred in conventional ALE thin filmprocesses because of the relatively slow production pace of the ALEmethod relative to other thin film growth techniques. The overall growthtime per substrate of a thin film structure can be reduced in a batchprocess to a more competitive level. For the same reason, largersubstrate sizes are also preferred.

[0012] In the deposition of thin films, the goal is to keep the processchambers continually running under controlled process conditions as tothe temperature, pressure and other process parameters so thatparticulate matter of the ambient air and other chemical impuritiescannot reach the substrates. Additionally, this arrangement eliminatesthe heating/cooling cycles that impair the reliability of processchambers and are time-consuming. Generally, a separate loading chamberis employed that is continually kept under a vacuum and to which thereactors are connected. Substrate loading thereto and unloadingtherefrom is accomplished by taking both the process chamber and theloading chamber to a vacuum, after which a valve between both chambersis opened and a robotic arm adapted into the loading chamber removes theprocessed substrate and loads a new substrate into the process chamber.Subsequently, the valve is closed and the process may be started afterthe substrate and the process chamber have attained the proper processconditions. Next, the processed substrate is moved via anothercontrollable valve from the loading chamber to an air lock pumped to avacuum, after which the valve is closed. Subsequently, the air lock canbe pressurized, whereby the substrate can be removed from the system viaa third valve opening into the ambient space. The new substrate to beprocessed is taken in the same fashion via the loading chamber into theprocess chamber.

[0013] Currently, process apparatuses equipped with this type of aloading chamber are available for single substrates only and they arenot suited for accommodating heavy substrate cassette units. Dependingon the batch and substrate size, such cassette units may weigh up to 200kg, whereby devices designed for their handling must have a sturdyconstruction. Moreover, the lubrication of bearings and other similarcomponents of the transfer means is problematic, because the lubricantrequired herein may affect the structure of the thin film to be grown.

[0014] The large cassette units used in conventional ALE depositionprocesses are assembled outside the process apparatus, after which theprocess chamber is opened and the cassette units are transferred asassembled entities into the process chamber. In the process chamber, thecassette unit is heated typically for 1-4 hours, processed for 2-4 hoursand cooled up to ten hours depending on the cassette unit size.Furthermore, the assembly/disassembly of the cassette unit is atime-consuming operation. The ratio of the processing time vs. the worktime required for other operations becomes even more disadvantageouswhen thin films of extremely shallow thickness (e.g., in the range 1-50nm) are to be grown and the growth period may take from one minute to afew minutes. Under these circumstances, a major portion of the overallprocess cycle time in regard to the actual thin film growth period islost in heating/cooling the reaction chamber structures, pressurizingthe reactor, disassembling and reassembling the reaction chamber,pumping to a vacuum and reheating the system.

[0015] It is therefore an object of the present invention to provide annovel type of ALE apparatus that reduces the amount of time lost inheating/cooling the reaction chamber structures, pressurizing thereactor, disassembling and reassembling the reaction chamber, pumping toa vacuum and reheating the system.

[0016] Accordingly, one aspect of the invention involves equipping theprocess chamber with a separate loading chamber that can be pressurizedindependently from the process chamber so that the loading of thecassette unit into the process chamber can be carried out under a vacuumor a low-pressure inert gas atmosphere. The loading chamber can becomplemented with preheating/cooling stations to shorten the overallprocessing cycle time. In a modified arrangement, a plurality of processchambers can be connected to each loading chamber. For moving thecassette unit, the reactor is provided with a transfer mechanism capableof accurately and sealably placing the cassette unit into its properposition in the process chamber and removing the same therefrom.

[0017] More specifically, the invention relates an apparatus thatcomprises at least one process chamber having a tightly sealableconstruction, at least one into the interior of said process chamberadaptable reaction chamber including a reaction space of which at leasta portion is movable, infeed means connected to the reaction space forfeeding reactants into the reaction space and outfeed means connected tothe reaction space for discharging excess reactants and reaction gasesfrom the reaction space, and at least one substrate adapted into saidreaction space. The apparatus further includes at least one loadingchamber in which the reaction space can be moved into and away from theprocess chamber and whose operating pressure can be controlledindependently from said process chamber.

[0018] The invention offers significant benefits. For example, with thehelp of the loading chamber, the cassette unit can be moved into theprocess chamber and out therefrom so that the process chamber is at alltimes kept under stabilized process conditions. Hence, the steps ofheating, pressurizing and pumping to a vacuum need not be carried outfor the entire process chamber, but instead, for the substrates only,thus improving the efficiency of process chamber vastly. Owing to theuse of the loading chamber, the interior parts of the process chamberare isolated from a direct connection to the ambient air, whereby thenumber of detrimental particles in the process chamber is reduced. Thetransfer mechanism employed in the embodiment of the invention iscapable of moving relatively heavy cassette unit constructions andlocating them accurately in a desired position within the processchamber. In another modified arrangement, a single loading chamber canbe connected to a plurality of process chambers adapted to producedifferent kinds of thin film structures so that a plurality of thin-filmlayers can be grown without the need for intermediate transfer of thecassette units to ambient air atmosphere. This reduces the risk ofpossible contamination and the required number of thermal cycles.

[0019] It should be noted that certain objects and advantages of theinvention have been described above for the purpose of describing theinvention and the advantages achieved over the prior art. Of course, itis to be understood that not necessarily all such objects or advantagesmay be achieved in accordance with any particular embodiment of theinvention. Thus, for example, those skilled in the art will recognizethat the invention may be embodied or carried out in a manner thatachieves or optimizes one advantage or group of advantages as taughtherein without necessarily achieving other objects or advantages as maybe taught or suggested herein.

[0020] It should also be noted that all of these embodiments areintended to be within the scope of the invention herein disclosed. Theseand other embodiments of the present invention will become readilyapparent to those skilled in the art from the following detaileddescription of the preferred embodiments having reference to theattached figures, the invention not being limited to any particularpreferred embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In the following, the invention will be described in greaterdetail with the help of exemplifying embodiments illustrated in theappended drawings, in which

[0022]FIG. 1 is a partially sectional view of an embodiment of theapparatus according to the invention; and

[0023]FIG. 2 is a layout diagram of another embodiment of the apparatusaccording to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0024] In the context of the present invention, the term “reactant”refers to a gas or a vaporizable solid or liquid starting materialcapable of reacting with the surface of the substrate. The ALE methodconventionally uses reactants selected from two separate groups. Theterm “metallic reactants” is used of metallic compounds which may evenbe elemental metals. Suitable metallic reactants are the halogenides ofmetals including chlorides and bromides, for instance, andorganometallic compounds such as the thd complex compounds. As examplesof such metallic reactants are Zn, ZnCl₂, Ca(thd)₂, (CH₃)₃Al and Cp₂Mg.The term “nonmetallic reactants” is used for compounds and elementscapable of reacting with metallic compounds. The latter group isappropriately represented by water, sulfur, hydrogen sulfide andammonia.

[0025] In the present context, the term “protective gas” is used whenreference is made to a gas which is admitted into the reaction space andis capable of preventing undesired reactions related to the reactantsand, correspondingly, the substrate. Such reactions include e.g. thereactions of reactants and the substrate with possible impurities. Theprotective gas also serves to prevent reactions between substances ofdifferent reactant groups in, e.g., the infeed piping. In the methodaccording to the invention, the protective gas is also advantageouslyused as the carrier gas of the vapor-phase pulses of the reactants.According to a preferred embodiment, in which reactants of differentreactant groups are admitted via separate infeed manifolds into thereaction pace, the vapor-phase reactant pulse is admitted from oneinfeed channel while the protective gas is admitted from another infeedchannel thus preventing admitted reactants from entering the reactantinfeed channel of another reactant group. Examples of suitableprotective gases are inert gases such as nitrogen and noble gases, e.g.,argon. The protective gas may also be an inherently reactive gas such ashydrogen gas selected to prevent undesirable reactions (e.g.,oxidization reactions) from occurring on the substrate surface.

[0026] According to the invention, the term “reaction chamber” includesboth the reaction space in which the substrate is located and in whichthe vapor-phase reactants are allowed to react with the substrate inorder to grow thin films as well as the gas infeed/outfeed channelscommunicating immediately with the reaction space. The channels serve toadmit the reactants into the reaction space (infeed channels) or toremove the gaseous reaction products and excess reactants of thethin-film growth process from the reaction space (outfeed channels). Asubstrate located in this kind of reaction chamber is subjected toalternately repeated surface reactions of at least two differentreactants used for producing a thin film. The vapor-phase reactants areadmitted repetitively and alternatingly, each reactant being fedseparately from its own source into the reaction chamber, where they areallowed to react with the substrate surface for the purpose of forming asolid-state thin film product on the substrate. Reaction products whichhave not adhered onto the substrate and any possible excess reactant areremoved from the reaction chamber in the vapor phase.

[0027] Herein, the term “substrate surface” is used to denote thatsurface of the substrate onto which the vapor-phase reactant flowinginto the reaction chamber impinges. In practice, said surface, duringthe first cycle of the thin-film growing process is constituted by thesurface of a substrate such as glass, for instance, or some otherstarting surface; during the second cycle the surface is constituted bythe layer formed during the first cycle and comprising the solid-statereaction product which is deposited by the reaction between thereactants and is adhered to the substrate, etc.

[0028] The term “process chamber” is used when reference is made to thespace in which the thin film growth process is carried out and which isisolated from its environment in a tightly sealable manner. The reactionchamber is located in the process chamber and, further, a single processchamber may incorporate a plurality of reaction chambers.

[0029] Now referring to FIG. 1, an apparatus having certain features andadvantages according to the present invention is illustrated. Theapparatus construction includes a loading chamber 1, which also servesas a loading gate, whose wall is partially sectioned in the Figure toelucidate the interior of the chamber 1. The illustrated apparatus alsoincludes a cold-walled process chamber 2, which is illustrated with onewall partially sectioned to elucidate the interior of the chamber. Acassette unit 3, which contains substrates and acts as the processspace, is shown resting on supports, such as, for example, forks 4,which are preferably mounted on a door 5 that, as will be explainedbelow, separates the loading chamber 1 from the process chamber 2. Abovethe cassette unit 3 is adapted a sprayhead 16, which contains thereactant infeed channels. In the process chamber 2 is a suction box 12,which is preferably permanently mounted. The cassette unit 3 and thesprayhead 16 can be mounted above the suction box 12. The illustratedsuction box 12 preferably houses the outfeed means of reaction gases andexcess reactants. The cassette unit 3, the sprayhead 16 and the suctionbox 12 together form the reaction chamber.

[0030] As mentioned above, the door 5 that also serves as the gate valvebetween the loading chamber 1 and the process chamber 2. An actuatormechanism 7 is adapted to move the door 5 within the loading chamber 1.A lateral transfer mechanism 6 is located above the cassette unit 3. Inthe illustrated arrangement, the later transfer mechanism is adapted togrip the cassette unit 3 during the lifting thereof by means of hooks.Both the actuator mechanism 7 and the top-side lateral transfermechanism 6 of the door 5 can use an eccentric cam 8 for actuating thelift movement and a ball screw 9 for actuating the horizontal movement.One advantage of these arrangements is a reliably tightly sealedimplementation of rotary motion feedthroughs 10. The electricalactuators 11 of the transfer means 6, 7, 8, 9 can be located outside theloading chamber 1 and the process chambers 2. Such an arrangement canavoid subjecting the electrical actuators 11 to breakthrough problemsthat may occur under a vacuum. Moreover, this arrangement makes themaintenance of the actuators 11 easier.

[0031] In use, the cassette unit 3 with the substrates placed thereinand the sprayhead 16 are transferred via a door 15 into the loadingchamber 1. The door 15 is then closed. As the steps of the ALE processare typically carried out at a pressure of about 0.1-30 mbar, theloading chamber 1 after the door 15 is closed is preferably pumped to apressure lower than the process pressure. For this purpose, the loadingchamber 1 is preferably equipped with a separate vacuum pump dedicatedto this task. After vacuum pumping, the door 5 separating the loadingchamber 1 from the process chamber 2 is preferably opened with the helpof the door actuator mechanism 7. The door 5 preferably is arranged tomove in the interior of the loading chamber in a direction essentiallyorthogonal to its seal surface. The lateral transfer mechanism 6, whichis preferably locked to the top of the cassette unit 3 by means ofhooks, transfers the cassette unit 3 with the sprayhead 16 ontovertically movable lift, such as, for example forks 4 mounted on theside of the door 5 facing the process chamber 2. Subsequently, thelateral transfer mechanism 6 is detached from the cassette unit 3. Thedoor can then be moved towards the process chamber 2 and the cassetteunit 3 with the sprayhead 16, which are resting on the forks 4, can belowered onto the suction box 12. Preferably, the cassette unit 3 islowered onto the suction box when the door is approximately 10-20 mmfrom a closed position of the door 5. In such an arrangement, the forks4 mounted on the door 5 are released before the end of the downwardmotion as the cassette unit 3 rests on the suction box 12. Thisarrangement relieves the door 5 from the additional load of the cassetteunit 3 when it is closed. This makes it easier for the door 5 to matewith its seat surface and thus impose a uniform linear pressure on theseal 13 as required for an efficient seal. The seating step can befurther facilitated by providing a pivoting mount 14 for the door 5.

[0032] In the illustrated arrangement, the cassette unit 3, thesprayhead 16 and the suction box 12 form a reaction chamber wherein thevapor-phase reactants are allowed to react with the substrate in orderto grow thin films. The infeed channels in the sprayerhead 16 serve toadmit the reactants into the reaction space between the substrates andoutfeed channels in the suction box 12 serve to remove the gaseousreaction products and excess reactants of the thin-film growth processfrom the reaction space. The substrates located are preferably subjectedto alternately repeated surface reactions of at least two differentreactants used for producing a thin film. The vapor-phase reactants areadmitted repetitively and alternatingly, each reactant preferably beingfed separately from its own source into the reaction chamber, where theyare allowed to react with the substrate surface for the purpose offorming a solid-state thin film product on the substrate. Reactionproducts which have not adhered onto the substrate and any possibleexcess reactant are removed from the reaction chamber in the vaporphase. Of course, to perform the above-described processes, theillustrated apparatus preferably includes a suitably configuredcontroller.

[0033] After the processing steps are completed, the cassette unit 3with the above-lying sprayhead 16 is preferably lifted off from abovethe suction box 12 by means of the forks 4. Next, the door 5 is openedand the cassette unit 3 is moved on the forks 4 into the loading chamber1. The lateral transfer mechanism 6 grips the cassette unit 3,preferably at its top, and transfers the cassette unit 3 with theabove-lying sprayhead 16 from the forks 4 to in front of the door 15 ofthe loading chamber 1. After the door 5 is closed, the loading chamber 1can be pressurized and the cassette unit 3 removed from the loadingchamber 1. Removal of the cassette unit 3 from the loading chamber 1 andloading of a new cassette unit into the loading chamber 1 can beperformed using, e.g., a carriage equipped with a fork lift mechanism.

[0034] Thermal expansion of the suction box 12 and the cassette unit 3may impose thermal stresses on the suction box 12 if it is supported tothe process chamber 2 by. for example, its edges. The magnitude of suchthermal expansion may mount up to several millimeters. These dimensionalchanges may complicate some process steps, such as, for example, thepositioning of the cassette unit 3 in the process chamber 2 during theautomated unload/load steps. Hence, the suction box 12 is preferablysupported to the wall structures of the process chamber 2 so that thecenter of the support point coincides at least substantially with thecenter point of the suction box 12. This provides the suction box 12with a greater degree of freedom to expand outward from its supportpoint and the positioning accuracy of the cassette unit 3 is improved.

[0035] A modified arrangement of the present invention is illustratedschematically in FIG. 2. In this arrangement, the loading chamber 1 ismade wider in its lateral dimension so as to provide the loading chamber1 with additional cassette unload sites by extending the reach of thelateral transfer mechanism 6. Thus, a single loading chamber 1 can beconnected to a plurality of process chambers 2. In such an arrangement,the process chambers 2 can be adapted to produce, for example, differenttypes of thin-film structures or to run the different steps of a giventhin-film growth process. The use of the expanded loading chamber 1offers a shorter processing time per substrate and other salientbenefits.

[0036] In addition to those described above, the invention may haveadditional modified arrangements. For example, a single process chamber2 may be adapted to house a plurality of reaction chambers. Furthermore,the loading chamber 1 may be complemented with an intermediate stationserving to heat the cassette unit 3 prior to its transfer into theprocess chamber 2 and/or to cool the cassette unit 3 prior to itstransfer of out from loading chamber 1. Such an arrangement can improvethe throughput capacity of the process chamber 2. In another modifiedarrangement, the cassette unit 3 can be transferred from the ambient airatmosphere into loading chambers 1 having a plurality of unloadpositions for cassette units 3 and respectively removed via separatepressurizing chambers. In such an arrangement, there is no need forpressurizing the large-volume loading chamber 1 in conjunction with thetransfer of the cassette unit 3.

[0037] In yet another modified arrangement, a gate valve can be used inaddition to or instead of a door 4 for sealing the process chamber 2from the loading chamber 1. In still yet another modified arrangement,the cassette unit 3 need not have a construction that must be moved asan entity. For example, the interior of the cassette unit 3 may beprovided with a holder into which the substrates are placed. The holdercan then moved from the loading chamber 1 into the process chamber 2 andthen away from the process chamber 2.

[0038] It should be noted that certain objects and advantages of theinvention have been described above for the purpose of describing theinvention and the advantages achieved over the prior art. Of course, itis to be understood that not necessarily all such objects or advantagesmay be achieved in accordance with any particular embodiment of theinvention. Thus, for example, those skilled in the art will recognizethat the invention may be embodied or carried out in a manner thatachieves or optimizes one advantage or group of advantages as taughtherein without necessarily achieving other objects or advantages as maybe taught or suggested herein.

[0039] Moreover, although this invention has been disclosed in thecontext of certain preferred embodiments and examples, it will beunderstood by those skilled in the art that the present inventionextends beyond the specifically disclosed embodiments to otheralternative embodiments and/or uses of the invention and obviousmodifications and equivalents thereof. In addition, while a number ofvariations of the invention have been shown and described in detail,other modifications, which are within the scope of this invention, willbe readily apparent to those of skill in the art based upon thisdisclosure. For example, it is contemplated that various combination orsubcombinations of the specific features and aspects of the embodimentsmay be made and still fall within the scope of the invention.Accordingly, it should be understood that various features and aspectsof the disclosed embodiments can be combined with or substituted for oneanother in order to form varying modes of the disclosed invention. Thus,it is intended that the scope of the present invention herein disclosedshould not be limited by the particular disclosed embodiments describedabove, but should be determined only by a fair reading of the claimsthat follow.

What is claimed is:
 1. A method for growing thin films onto the surface of a substrate comprising: placing at least one reaction chamber into a loading chamber; lowering the pressure in said loading chamber; moving said at least one reaction chamber into a process chamber; exposing the reaction chamber to alternating pulses of vapor-phase reactants such that a substrate located within said reaction space is exposed to alternating surface reactions of said vapor-phase reactants.
 2. The method of claim 1, further comprising: placing an inlet to said at least one reaction chamber into said loading chamber; and moving said inlet with said at least one reaction chamber into said process chamber.
 3. The method of claim 1, wherein moving said at least one reaction chamber into said process chamber further includes placing said at least one reaction chamber on an outlet of said reaction space.
 4. The method of claim 1, further comprising: removing said at least one reaction chamber from said process chamber and placing said at least one reaction chamber into said loading chamber; pressurizing said loading chamber; and removing said at least one reaction chamber from said loading chamber. 